Ventricular fibrillation (VF) is the most common arrhythmia causing sudden cardiac death. Electrical defibrillation remains the method of choice for the treatment of VF. However, the probability of a successful defibrillation decreases after a prolonged duration of VF. Adequate coronary perfusion during cardiopulmonary resuscitation (CPR) is crucial for successful defibrillation following a prolonged VF (or late VF). Studies have demonstrated that a brief period of myocardial perfusion with CPR before defibrillation could improve outcome for selected patients in whom defibrillation is not likely to succeed.
Since out-of-hospital cardiac arrest (OOHCA) does not allow invasive measurement of coronary perfusion status, noninvasive methods have been developed to monitor coronary perfusion status. One such method is based on the VF waveform of surface electrocardiogram (ECG). However, there remains a need to rapidly distinguish early VF and late VF so as to provide timely guidance on the CPR and electrical defibrillation treatments to the patient.